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Structure determination of neutral MgO clusters--hexagonal nanotubes and cages
Marko Haertelt1, André Fielicke, Gerard Meijer
1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany.
Physical Chemistry Chemical Physics : PCCP
|January 19, 2012
Summary
Neutral magnesium oxide clusters ((MgO)n) were studied using infrared spectroscopy. Hexagonal tubes were observed for (MgO)(3k) clusters, while cage-like structures formed for other sizes, revealing unique cluster geometries.
Area of Science:
- Physical Chemistry
- Materials Science
- Computational Chemistry
Background:
- Understanding the structure of small clusters is crucial for predicting material properties.
- Magnesium oxide (MgO) clusters exhibit unique structural motifs that differ from bulk MgO.
Purpose of the Study:
- To determine the structural properties of neutral magnesium oxide clusters ((MgO)n) for n = 3-16.
- To compare experimental vibrational spectra with theoretical predictions to identify cluster structures.
Main Methods:
- Gas-phase infrared (IR) spectroscopy using a tunable IR-UV two-color ionization scheme.
- Size-selective IR spectrum measurement for (MgO)n clusters (n=3-16).
- Comparison of experimental spectra with theoretical calculations of global minimum structures from a hybrid ab initio genetic algorithm.
Main Results:
- Experimental vibrational spectra confirm theoretical predictions for (MgO)n cluster structures.
- (MgO)(3k) clusters (k=1-5) form stable hexagonal tubes.
- Intermediate-sized clusters (n≠3k) adopt cage-like structures incorporating hexagonal (MgO)(3) rings.
- Cubic (MgO)(4) was identified, but no bulk-like structures were observed for n=3-16.
Conclusions:
- Magnesium oxide clusters exhibit distinct structural transitions from small clusters to bulk.
- Hexagonal tube and cage-like structures are prevalent in neutral (MgO)n clusters.
- The study provides experimental validation for theoretical predictions of cluster geometries.
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